The present invention relates to a non-sealable, multi-layer polypropylene film and to the production and use of the same.
Sealable and non-sealable polypropylene films have been described in numerous publications. A problem which frequently occurs in these films is connected with the adhesion of coatings, printings or adhesives to films of this kind, which is usually insufficient owing to the highly non-polar character of polyolefins. In view of the increasing strengthening of environmental protection regulations, aqueous coating systems have gained in importance. These systems, however, lead to particularly great adhesive difficulties due to their polarity.
EP-A-0 234 758 describes a polypropylene film and states that aqueous coatings are readily applicable to this film. A substantial drawback of this film, however, is that it possesses good coating qualities only shortly after its production, but loses these qualities during storage. In the preparation of laminates from this film using water-based adhesives, it has been found that curing of the adhesives is retarded considerably relative to storage time.